Perhaps you should try some spelling variations:
occasional letters » occasional prayers, occasional papers
occasional writer » occasions written
occasional letter » occasional verse
occasional notess » occasional notices, occasional poems, occasion notes

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (( ((occasional letters) OR (occasional writer)); occasional letter ) OR ( occasional notess; occasional notes )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( ((occasional letters) OR (occasional writer)); occasional letter ) or ( occasional notess; occasional notes ))".
• Adding a wildcard symbol may retrieve word variants: (( ((occasional letters) OR (occasional writer)); occasional letter ) or ( occasional notess; occasional notes ))*.